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Despite success in cutting down on contrast media volume, the Avert system didn't reduce the risk of acute kidney injury (AKI) after coronary angiography, a trial found.

Operators used 85.6 mL of contrast when patients were randomized to hydration plus manual contrast injection with the contrast modulation system (versus 101.3 mL with hydration alone, P=0.02), and 114 mL in the subset of percutaneous coronary intervention (PCI) recipients (versus 147 mL with hydration alone, P=0.001), according Roxana Mehran, MD, of Mount Sinai Hospital in New York City, and colleagues.

The difference between hydration alone and hydration plus the Avert system was biggest among patients with at least three lesions treated by PCI (124 versus 232 mL, P=0.01), they stated in .

However, the investigators could find no difference in contrast-induced AKI rates between the two groups (27.0% versus 26.6%, P=0.70).

Avert is a device that diverts contrast during coronary injection; the amount of contrast medium sent away depends on injection force and the setting selected on the contrast modulator.

"Future trials designed specifically for a patient population requiring higher contrast volume, such as complex PCI, may be more reflective of potential risk reduction," suggested Charles Chambers, MD, of Penn State Hershey Medical Center, who recalled other failed attempts at reducing AKI after coronary angiography -- namely iso-osmolar contrast, N-acetylcysteine, and sodium bicarbonate.

"As I review these studies, I recall my Vermont professor saying, 'You can't make a silk purse out of a sow's ear.' End-stage renal disease is end stage; critically ill patients are critically ill. No contrast dose is entirely safe in high-risk patients with other AKI etiologies, including dehydration, drug toxicities, hemodynamic instability, and atheroembolic or cholesterol-embolic disease," Chambers wrote in an accompanying commentary.

For now, while researchers continue to seek a cure for contrast-induced AKI, clinicians must stick to pre- and post-hydration and contrast dose reduction from the start of each procedure, he said.

Conducted at 39 centers, the prospective trial randomized 578 consecutive eligible patients to hydration with or without the Avert system. Participants were eligible if they were at high risk for contrast-induced AKI (having a baseline estimated glomerular filtration rate [eGFR] of 20-30 mL/min/1.73 m² or eGFR 30-60 mL/min/1.73 m² and two additional risk factors).

Using the Avert system, operators maintained acceptable image quality during coronary angiography and PCI in 99.3% of the cases.

Groups shared well-matched characteristics at baseline. The population had a median age of 72 and 1.6 mg/dL mean baseline serum creatinine. Nearly two-thirds had diabetes.

PCI followed coronary angiography in 42.2% of cases. Mehran's group noted that having most patients undergo diagnostic procedures only could have reduced their power to show a difference in contrast-induced AKI between groups.